Vancomycin hydrochloride is an amphoteric glycopeptide antibiotic produced by fermentation of Actinomycetes Amycolatopsis orienatalis under controlling conditions, which has a molecular formula C66H75Cl2N9O24.HCl and a molecular weight of 1.486. Vancomycin hydrochloride acts by binding the C-terminal D-Ala-D-Ala peptides, which inhibits the synthesis of cell walls and also changes the permeability of cell membranes as well as synthesis of RNA. Vancomycin hydrochloride is particularly used for the initial treatment of serious or severe infections caused by staphylococci resistant to β-lactam antibiotics as well as in patients who are penicillin-sensitive or do not respond to penicillin or cephalosporine. It is reported by early literatures that vancomycin hydrochloride has serious kidney toxicity and ototoxicity and thus has not been widely used in clinical. However, due to a large number of uses of antibiotics recently, it would result in increasing clinical infections of methicillin-resistant Staphylococcus aureus (MASA), makes usages amount of vancomycin hydrochloride increased year by year. Therefore, it is very important to reduce toxicity of vancomycin hydrochloride and increase safety of usage of medicinal vancomycin hydrochloride, wherein improving the purity of medicinal vancomycin hydrochloride is an effective means. Recently, with continuous development of science and technology, persons skilled in the art constantly have improved purity of vancomycin hydrochloride, and severe kidney toxicity and ototoxicity caused by vancomycin hydrochloride are reduced constantly. Based on the above reasons, it is very important to develop a purification process of vancomycin hydrochloride with a higher purity, simple and feasible, and suitable for industrial production.
Vancomycin molecule is composed of two basic structures, including a saccharide group, α-o-vancosamine-β-o-glucosyl, and a heptapeptide backbone. The structure of vancomycin determines its instability, and vancomycin molecules is degraded to produce degradation products under the condition of acid, alkali or high temperature. In the meanwhile, multiple free phenolic hydroxyl groups of the structure are easily oxidized to quinoid. It has been reported by literatures that vancomycin would be hydrolyzed under the conditions of acid and high temperature to produce desvancosaminyl vancomycin or aglucovancomycin, by taking off one or two glycosyl, and degraded into amino vancomycin by taking off acylamino having two isomers under weak acidic condition. Based on these features of chemical structure of vancomycin, it is difficult to produce vancomycin hydrochloride with high purity
It has been decades histories for developing products of vancomycin hydrochloride. In early preparation technology, vancomycin hydrochloride is prepared by crystallization using solvents such as methanol, ethanol, isopropanol and acetone etc. and precipitation using ammonium chloride or sodium chloride. However the purity is generally not high due to many impurities especially many structural analogues of vancomycin in the vancomycin fermentation medium. So it is difficult to meet the European Pharmacopoeia Standards with chromatographic purity of more than 93%.
The technology has been widely used in the separation and purification of vancomycin hydrochloride recently, with development of chromatographic separation technology of all kinds of medium. CN200710187300.5 performs chromatography using ion-exchange fillers such as glucan gel SEPHADEX® CM-25, agarose SP SEPHAROSE® or agarose CM SEPHAROSE®, wherein a mobile phase is ammonium bicarbonate of 4-6%, to obtain vancomycin hydrochloride with a chromatographic purity of 95%˜98%, and then salting-out precipitate by adding sodium chloride solution, and afterwards separate and, wash by ethanol and dry to obtain vancomycin hydrochloride. The purity of vancomycin hydrochloride obtained by the method is higher, however the recovery rate is not high. Besides, this ion exchange chromatography method is not very ideal for removing pigment. So the product produced by the method is not very ideal in color appearance and solution absorbance.
PCT Patent Application No. WO2006061166 uses a reverse phase silica gel (octadecyl silica gel) with a, particle size of 5 μm as chromatographic medium, a mobile phase including an aqueous solution of 5 mM of ammonium acetate and 3% of methanol solution with pH=4.0, 2% of an analytical agent with n-pentanol in the mobile phase, to collect vancomyin hydrochloride with a chromatographic purity of more than 97.5%. Afterwards, the vancomyin hydrochloride is concentrated under vacuum to a concentration of 140 mg/ml, and the add methanol, then adjust pH=8.5 to 9.0 with an aqueous solution of ammonia, and cool to 0° C. to produce precipitate, and then separate and wash with methanol, and then dissolve the separation with water and adjust pH=3.2 and crystallize with isopropanol, and dry in vacuum, to obtain vancomycin hydrochloride with a purity of 97-99.3%. There are some deficiencies in the method of the patent, especially it is difficult for commercial expansive production. First of all, the metod uses different solvents as a mobile phase and an eluate, so it is difficult to recover solvents; Secondly, it can not reach a chromatographic purity of 99% for one-time due to reverse phase purification in the method. So it needs two steps in solvent crystallization, finally to obtain vancomyin hydrochloride under vacuum drying. However residual solvents can't be effectively removed in the solvent crystallization, and residual solvents can't meet the requirements of ICH. Finally, the product yield is not ideal in this method because of many steps.
Therefore, it may be seen from current literatures that no method of preparing vancomycin hydrochloride with high purity (chromatographic purity of more than 99%) is suitable for commercial production due to many deficiencies. In view of medication safety of vancomycin hydrochloride, methods for preparing vancomycin hydrochloride with high purity are needed.